Investigation of Mixed Chiral Selectors of Different Metal Ion-L-Alanine Complex and β-Cyclodextrin on the Chiral Separation of Dansyl Amino Acids with Capillary Electrophoresis

Chiral separation of dansyl amino acids by capillary electrophoresis using mixed selectors of Mn (II)-L-alanine complex and β-cyclodextrin (β-CD) was studied. Resolution was considerably superior to that obtained by using either Mn(II)-L-alanine complex or β-CD alone. The effects of separation parameters, such as pH value of buffer solution, capillary temperature, the concentration of Mn (II)-L-alanine complex, the types of CD and ligand on the migration times and resolutions were investigated. Six different transition metal complexes, Cu(II), Zn(II), Co(II), Ni(II), Hg(n) and Cd(n)-L-alanine complexes have been employed and compared with Mn(II) complex. Differences in retention and selectivity were found. The substitution of Cu(II), Zn(H), Co(II) and Ni(II) for Mn (II) resulted in a better chiral resolution while Hg(II) and Cd (II) showed poorer resolution abilities. The chiral separation mechanism was also discussed briefly.